Abstract

Previous studies have shown that direct-acting dopamine agonists modulate the multisecond oscillations which are present in globus pallidus spike trains in vivo in awake rats. To investigate possible modulation by endogenous dopamine and by other monoamines, and by drugs with abuse potential, cocaine or selective monoamine uptake blockers were injected systemically during extracellular recording of single globus pallidus neurons and the results analyzed with spectral and wavelet methods. Both cocaine and the selective dopamine uptake blocker GBR-12909 significantly shortened the period of multisecond oscillations, as well as increasing overall firing rate. Cocaine effects were blocked by dopamine antagonist pretreatment, as well as by N-methyl-D-aspartate receptor antagonist (MK-801) pretreatment. Desipramine and fluoxetine (blockers of norepinephrine and serotonin uptake, respectively) had no significant effects on multisecond oscillations. The results suggest that dopamine has a primary role among monoamines in modulating multisecond oscillations in globus pallidus activity, and that tonic dopaminergic and glutamatergic transmission is necessary for normal slow oscillatory function.